Fuel injection valve

ABSTRACT

The invention relates to a fuel injection valve having an axially movable valve needle ( 13 ) having at least one closing body support ( 17 ) and a spherical valve closing body ( 18 ). The closing body support ( 17 ) accommodates the valve closing body ( 18 ) in a downstream end area ( 46 ). The valve closing body ( 18 ) has at least one flattened zone ( 24 ) on its surface, whereby the flattened area has an axial extension component, and whereby at least one channel ( 47 ) for a flow of fuel is formed between the at least one flattened zone ( 24 ) and an inner wall of the closing body support ( 17 ). 
     The fuel injection valve is especially well suited for use in fuel injection systems of mixture-compressing, SI internal combustion engines.

FIELD OF THE INVENTION

The present invention relates to a fuel injection valve.

BACKGROUND OF THE INVENTION

A fuel injection valve in the form of an electromagnetically actuatedvalve is described, for example in German Patent Application No. 38 31196, in which a valve needle is formed from an armature, a tubularconnecting piece and a spherical valve closing body. The armature andthe valve closing body are connected by the connecting piece, theconnecting piece serving as a direct closing body support to which thevalve closing body is solidly attached by a welded joint. The connectingpiece has a multiplicity of flow openings through which the fuel canexit from an interior passageway and flow outside of the connectingpiece to the valve closing body or to a valve seat face cooperating withthe valve closing body. In addition the roll-bent connecting tube has alongitudinal slot running its entire length, the hydraulic flowcross-section section of which is large so that fuel coming from theinterior passageway can flow through it quickly. Most of the fuel to beinjected already flows out of the connecting piece over its length,while a small remnant portion does not exit from the connecting pieceuntil immediately at the sphere surface.

German Patent Application No. 197 12 590 is an electromagneticallyactuated valve that has an axially movable valve needle composed of anarmature, which is either itself a closing body support or is connectedto a closing body support, and a spherical valve closing body. Theclosing body support here accommodates the valve closing body in adownstream end area of the valve closing body. To do this, the end areaencompasses the valve closing body so that at least one channel directlyconnected with a longitudinal bore of the closing body support is formedon the surface of the valve closing body. The end area extends herebeyond the equator of the valve closing body. A solid connection isachieved by edge-forming or press-fitting.

Shaping out diagonally running grooves or flattened zones on the surfaceof spherical valve closing bodies of fuel injection valves is alreadydescribed, for example in U.S. Pat. No. 5,199,648 and German PatentApplication No. 44 08 875, the grooves or flattened zones being usedexclusively for angled impingement of the fuel to be injected. The flowtoward these formed closing body geometries occurs in this case fromoutside a tubular connecting piece of the valve needle and not againstthe spherical surface starting from an inner opening of the connectingpiece, which functions as a closing body support.

A fuel injection valve that has a valve needle with a spherical valveclosing body can be inferred from U.S. Pat. No. 4,483,485. The sphericalvalve closing body can also be provided with a horizontal flattened zonethat extends inside the connecting piece of the valve needle being usedas the closing body support. In order to enable a flow of fuel from aninner opening of the connecting piece to the valve seat, eithertransverse openings or several slotted openings that open toward thevalve closing body are provided in the wall of the connecting piece. Forall embodiments of the valve needle described in this specification, anopening geometry specially built into the closing body support andrequiring additional manufacturing or machining steps is needed for theoutflow of the fuel.

SUMMARY

The fuel injection valve according to the present invention has theadvantage that it can be produced in an especially simple and economicalmanner. For this purpose a spherical valve closing body is provided withat least one flattened zone having an axial extension component and issolidly connected with a sleeve-shaped closing body support. The closingbody support can be fabricated to be rotationally symmetric for this ina very simple way, without the necessity of incorporating any kinds ofopening geometry for the outlet of fuel on its exterior contour. Thusall machining steps that are typically needed for such additional flowopenings are omitted. The end area of the closing body supportencompasses the valve closing body in such a way that it forms one ormore channels—corresponding to the number of flattened zones—directly onthe surface of the valve closing body through which fuel can flowunhindered from the interior longitudinal bore coming toward a valveseat face. In this way an optimal flow to the metering area of the valveis achieved with little manufacturing effort.

Additional advantageous embodiments and improvements of the fuelinjection valve are possible.

It is advantageous to form the at least one flattened zone at an angleto the valve longitudinal axis of between 12 and 25° and to have theflattened zone run beyond a spherical equator of the valve closing bodyin the downstream direction.

In a especially advantageous way an magent armature can itself be useddirectly as the closing body support so that together with the valveclosing body a two part valve needle is formed. A valve needle of thistype can be produced especially simply and economically, and due to thereduced number of parts has only a single connecting piece.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a sectional view of a fuel injection valve according to thepresent invention;

FIG. 2 is a sectional view of a first exemplary embodiment of a valveneedle;

FIG. 3 is a schematic view illustrating a fuel flow against the valveneedle shown in FIG. 2;

FIG. 4 is a sectional view of a second exemplary embodiment of a valveneedle;

FIG. 5 is a schematic view illustrating a fuel flow against the valveneedle show in FIG. 4; and

FIG. 6 is a sectional view of third exemplary embodiment of a valveneedle.

DETAILED DESCRIPTION

The fuel injection valve according to the present invention, which isdepicted in part in simplified representation for purposes of example inFIG. 1 and is in the form of an injection valve for fuel injectionsystems of mixture-compressing SI internal combustion engines, has anessentially tubular core 2 that is encompassed by a magnet coil 1 andserves as an inner pole and in part as a fuel passageway. Together withan upper, disk-shaped covering element 3, the core 2 enables anespecially compact design of the injection valve in the area of themagnet coil 1. The magnet coil 1 is encompassed by an outerferro-magnetic valve casing 5 as an outer pole that completelyencompasses the magnet coil 1 in the circumferential direction and atits top end is solidly connected with the covering element 3, e.g. by awelded joint 6. To close the magnetic circuit, the valve casing 5 has astaggered design at its lower end so that a guide section 8 is formedwhich, in similar fashion as the covering element 3, axially encompassesthe magnet coil 1 and which represents the border of the magnet coilarea 1 below or in the downstream direction.

The guide section 8 of the valve casing 5, the magnet coil 1 and thecovering element 3 form an inner opening 11 or 58 running concentricallywith respect to a valve longitudinal axis 10. A longitudinally extendedsleeve 12 extends in the opening 11 or 58. An inner longitudinal opening9 of the ferritic sleeve 12 serves in part as the guide opening for avalve needle 13 that is axially movable along the valve longitudinalaxis 10. When viewed in the downstream direction, sleeve 12 terminatesfor example in the area of the guide section 8 of the valve casing 5,the sleeve 12 being solidly attached to the valve casing by a weldedjoint 54, for example.

In the exemplary embodiment represented in FIG. 1, the valve needle 13is formed by a tubular closing body support 17, which also functions asan armature and an essentially spherical valve closing body 18. As shownin FIG. 6, the valve needle 13 can also be formed from three pieces byan armature 17′, a closing body support 17 and a valve closing body 18.In addition to the axially movable valve needle 13, the stationary core2 is also arranged in the longitudinal opening 9 of the sleeve 12. Alongwith the guide of the closing body support 17 or the receptacle of thecore 2, the sleeve 12 also fulfills a sealing function so that there isa dry magnet coil 1 in the injection valve. This is also achieved byvirtue of the disk-shaped covering element 3 completely covering themagnet coil 1 on its top side. The inner opening 58 in the coveringelement 3 enables the sleeve 12, and thus also the core 2, to beconfigured as elongated so that both components protrude through theopening 58 above the covering element 3.

A valve seat body 14 that has a fixed valve seat face 15 as a valve seatis connected on the lower guide section 8 of the valve casing 5. Thevalve seat body 14 is solidly attached to the valve casing 5 by a secondwelded joint 16 produced by a laser, for example. A flat perforatedinjection disk 20 is arranged on the downstream face of the valve seatbody 14, for example in a recess 19, the fixed connection of valve seatbody 14 and perforated injection disk 20 being realized by acircumferentially sealed welded joint 21. The tubular closing bodysupport is solidly attached on its downstream end facing the perforatedinjection disk 20 with the spherical valve closing body 18, for exampleby welding. Closing body support 17 has an inner longitudinal bore 23through which fuel flows and out of which it exits downstream and canflow along, in the area of at least one flattened zone 24 that isdirectly on valve closing body 18 and has an axial extension component,until it reaches valve seat face 15.

The actuation of the injection valve is accomplished in a conventionalmanner e,g., electromagnetically. However, it must be emphasized that apiezoelectric actuator can also be used for the actuation of the valveneedle 13. The electromagnetic circuit with the magnet coil 1, the innercore 2, the outer valve casing 5 and the armature 17 are all used toproduce the axial motion of the valve needle 13, that is to open theinjection valve against the spring force of a return spring 25 or toclose the valve. The closing body support 17 functioning as an armatureis aligned with the end on the core 2 opposite the valve closing body18.

Spherical valve closing body 18 cooperates with conical valve seat face15, which narrows in the direction of flow and which is made in valveseat body 14 axially downstream from a guide opening 26. The perforatedinjection disk 20 has at least one injection opening, or for examplefour injection openings 27, formed by eroding or stamping.

An adjustment sleeve 29 outside of the return spring 25 is inserted intoa flow hole 28 of the core 2 running concentrically with respect to thevalve longitudinal axis 10, the flow hole being used to feed the fuel inthe direction of the valve seat face 15. The adjustment sleeve 29 isused for the adjustment of the preliminary spring tension of the returnspring 25 adjacent to the adjustment sleeve 29, the return spring inturn pushing with its opposite side against an insert 31 solidlyattached to the closing body support 17, a setting of the dynamicinjection quantity being made with the adjustment sleeve 29.

Such an injection valve is distinguished by its especially compactdesign, so that a very small, manageable injection valve is produced.The valve casing 5 has for example an outer diameter of only 11 mm. Thepreviously described components form a preassembled independent assemblythat can be characterized as a functional part 30. The pre-adjusted andpre-assembled functional part 30 has for example a top face 32 abovewhich for instance two connector pins 33 protrude. The electricalcontacting of the magnet coil 1 and thus its excitation are accomplishedby the electrical contact pins 33, which are used as electricalconnecting elements.

A connecting part (not shown), which is primarily distinguished in thatit includes the electrical and hydraulic connection of the injectionvalve, can be attached to such a functional part 30. A hydraulicconnection of the connecting part (not shown) and the functional part 30is accomplished in the fully mounted injection valve by flow holes ofboth assemblies being situated in relation to one another such that anunhindered circulation of the fuel is guaranteed. Here the face 32 ofthe functional part 30 for example is then directly adjacent to a lowerface of the connecting part and is solidly attached to it. In theassembly of the connecting part on the functional part 30, the part ofthe core 2 and the sleeve 12 extending above the face 32 can protrudeinto a flow hole of the connecting part to increase the connectionstability. For secure sealing, the connecting area has, for example, asealing ring 36 that encompasses the sleeve 12 bearing on the face 32 ofthe covering element 3. In the completely assembled valve, the contactpins 33 serving as electrical connecting elements make a secureelectrical connection with the corresponding electrical connectingelements of the connecting part.

FIG. 2 shows a valve needle 13 in an enlarged scale compared to FIG. 1.The tubular closing body support 17 is designed as a rotary componenthaving a multiple staggered outer contour. An annular guide surface 40,for example, that is used to guide the axially movable valve needle 13into the sleeve 12 is formed on the outer perimeter of the closing bodysupport 17. The closing body support 17 fabricated for example from aferritic material (chromium steel) has an upper stopping face 42opposite the core 2 that is provided with a wear-resistant coating, i.e.is chromed.

The inner longitudinal bore 23 in the closing body support 17 has anessentially circular cross-section. Overall, the closing body support 17is designed as rotationally symmetric in an advantageous way. Theessentially spherical valve closing body 18 has on its outer perimeterat least one flattened zone 24 with an axial extension component. In adownstream end area 46, the closing body support 17 surrounds the valveclosing body 18, which also protrudes partially into the longitudinalbore 23 of the closing body support 17. In the area in which the closingbody support 17 stands upright on the valve closing body 18, a fixedattachment is provided, for example by welding. The at least oneflattened zone 24 is formed on the valve closing body 18 such that itprotrudes into the longitudinal bore 23. This ensures that there is atleast one channel 47 between the inner wall of the closing body support17 and the flattened zone 24 through which the fuel supplied in thelongitudinal bore 23 and flowing along the valve closing body 18 isrouted in the direction of the valve seat face 15.

The angle of the flattened zone 24 to the valve longitudinal axis 10 is,for example, between 12° and 25°. However, other angles between 10° and50° are also conceivable. An additional flattened zone 24′ that is forexample vertical and thus parallel to the valve longitudinal axis 10 canalso adjoin the diagonally inclined flattened zone 24. In this case atransitional edge 48 from the first flattened zone 24 to the secondflattened zone 24′ lies further upstream from a sphere equator 49 of thevalve closing body 18. The flattened zone 24′ clearly extends past thesphere equator 49 in the downstream direction so that an essentiallycentral flow of fuel along the valve closing body 18 is produced, as issymbolically indicated by an arrow in FIG. 3.

FIG. 4 shows a second exemplary embodiment of a valve needle 13 in whichthe parts that are the same or function the same as the sampleembodiment represented in FIG. 2 are designated by the same referencenumbers. The valve needle 13 shown in FIG. 4 is distinguished in thatthe flattened zone 24 is not segmented and steadily runs at a constantangle of between 12° and 25° to the valve longitudinal axis 10 beyondthe sphere equator 49. Symbolically shown in FIG. 5 by several arrows isthat such an embodiment makes it possible for the flow of fuel to fanout more, which can be advantageous for a more broadly spread flowagainst the valve seat face 15.

FIG. 6 shows an additional exemplary embodiment of a valve needle 13. Inthis sample embodiment of the valve needle 13, the armature 17′ and thevalve closing body 18 are connected to each other by a sleeve-shapedconnecting part, the connecting part then forming the closing bodysupport 17. The connections to the valve needle 13 are produced here forexample by welding. The functions and geometric ratios already describedpreviously for the closing body support 17 functioning as an armatureare equally valid for the closing body support 17 representing aconnecting part in FIG. 6. The valve closing body 18 corresponds forexample to that of the sample embodiment shown in FIG. 4. In principlemore than one flattened zone 24 can be provided.

In addition to making the closing body support 17 as a turned part orcold-pressed part, embodiments are also conceivable in which it is asintered part or MIM (metal injection molding) part.

What is claimed is:
 1. A fuel injection valve having a valvelongitudinal axis, the fuel injection valve comprising: a fixed valveseat; a valve needle movable along the valve longitudinal axis, thevalve needle including at least one closing body support and asubstantially spherical valve closing body, the valve closing body beingsolidly attached to them closing body support, the valve closing bodycooperating with the fixed valve seat, the closing body supportincluding an inner longitudinal bore extending up to a surface of thevalve closing body; and an actuator for actuating the valve needle;wherein the valve closing body includes at least one flattened zonehaving an axial extension component on a surface thereof and wherein atleast one channel for a flow of fuel is formed between the at least oneflattened zone and an inner wall of the closing body support.
 2. Thefuel injection valve according to claim 1, wherein the at least oneflattened zone is arranged at a diagonally inclined angle relative tothe valve longitudinal axis.
 3. The fuel injection valve according toclaim 2, wherein the angle is between 12° and 25°.
 4. The fuel injectionvalve according to claim 1, wherein the flattened zone is formed ofseveral sections, one flattened zone arranged at a diagonally inclinedangle relative to the valve longitudinal axis and another one flattenedzone arranged parallel to the valve longitudinal axis.
 5. The fuelinjection valve according to claim 4, wherein the valve closing bodyincludes a sphere equator and wherein a transitional edge is arrangedbetween two flattened sections upstream of the plane of the sphereequator.
 6. The fuel injection valve according to claim 1, wherein atleast one flattened zone extends in a downstream direction beyond asphere equator of the valve closing body.
 7. The fuel injection valveaccording to claim 1, wherein the closing body support is configured asa magnet armature.
 8. The fuel injection valve according to claim 1,wherein the closing body support includes a connecting part connectingan armature and the valve closing body.
 9. A fuel injection valve havinga valve longitudinal axis and including a fixed valve seat, a valveneedle movable along the valve longitudinal axis, the valve needlefurther including at least one closing body support and a substantiallyspherical valve closing body, the valve closing body being solidlyattached to the closing body support, the valve closing body cooperatingwith the fixed valve seat and including at least one flattened zonehaving an axial extension component on a surface thereof, the closingbody support further including an inner longitudinal bore extending upto a surface of the valve closing body, and an actuator for actuatingthe valve needle, the fuel injection valve being made according to aturning or cold-pressing process.
 10. A fuel injection valve having avalve longitudinal axis, the fuel injection valve comprising: a fixedvalve seat; a valve needle movable along the valve longitudinal axis,the valve needle including at least one closing body support and asubstantially spherical valve closing body, the valve closing body beingsolidly attached to the closing body support, the valve closing bodycooperating with the fixed valve seat, the closing body supportincluding an inner longitudinal bore extending up to a surface of thevalve closing body; and wherein the valve closing body includes at leastone flattened zone having an axial extension component on a surfacethereof and wherein at least one channel for a flow of fuel is formedbetween the at least one flattened zone and an inner wall of the closingbody support, the at least one flattened zone being formed of more thanone section, each section at a different angle with respect to the valvelongitudinal axis.